Changes and prediction on metabolic function of intestinal microflora in severe burn patients at early stage by 16S ribosomal RNA sequencing

Objective: To analyze the changes and predict the metabolic function of intestinal microflora in severe burn patients at early stage by 16S ribosomal RNA (rRNA) sequencing. Methods: In the prospective observational study, 48 patients with severe burns who met the inclusion criteria and were admitted to Department of Burns and Plastic Surgery of Affiliated Hospital of Jiangsu University from January 2018 to December 2019 were included the burn group, and 40 healthy volunteers who met the inclusion criteria and underwent health examination at the Physical Examination Center of Affiliated Hospital of Jiangsu University in the same period were included in healthy group. Stool samples were collected from patients in burn group in about 1 week after admission and from healthy volunteers on the day of physical examination. The 16S rRNA V4 gene sequencing was performed in the stool of patients in burn group and volunteers in healthy group to analyze the relative abundance of various bacteria. The operational classification unit (OTU) was divided by Mothur software, and the thermal map of fecal micro flora structure was drawn. The OTU number, Chao1 index, Ace index, and Shannon index of stool microflora were analyzed by QIIME1.9.0 software. The principal component analysis (PCA) for relative abundance of stool microflora was preformed by Canoco Software 50. The metabolic function of stool microflora was predicted by Kyoto Encyclopedia of Genes and Genomes. Data were statistically analyzed with independent sample t test, Mann-Whitney U test, and Bonferroni correction. Results: The relative abundance of Bacteroides, Enterococcus, Acinetobacter, Macrococcus, and Staphylococcus in feces of patients in burn group was significantly higher than that of volunteers in healthy group (Z=-5.20, -2.37, -5.17, -4.41, -6.03, P 0.05. The metabolic levels of alanine-aspartate-glutamate, arginine-proline, cysteine-methionine, glycine-serine-threonine, phenylalanine, tryptophan, and tyrosine in amino acid, tricarboxylic acid cycle, glucose and mannose, galactolipin, glycolysis/gluconiogenesis, starch and sucrose in carbohydrate of fecal microflora of patients in burn group were significantly lower than those of volunteers in healthy group (Z=-4.75, -4.54, -4.75, -4.62, -3.71, -3.28, -4.19, -3.82, -4.72, -4.35, -4.75, -4.71, P 0.05). Conclusions: There were significant differences in intestinal microflora between severe burn patients at the early stage and healthy people. In burn patients, the species and diversity of microflora were decreased, and the nutrient metabolism level was decreased.